Pneumatic tires for vehicles can be classified into two general types: (1) the so-called bias in which the carcass reinforcing cords extend diagonally relative to the circumferential midplane of the tire; and (2) the radial in which the carcass reinforced cords extended essentially 90.degree. relative to the circumferential midplane of the tire. The radial type tires have a number of important advantages over bias tires among which are improved rate of tread wear and less power loss. However, it has been found that tires in which the principal or only sidewall reinforcement is provided by essentially radially extending cords subject the wheel rims on which the tires are mounted to greater stresses than do bias tires of the same size. This has not been of material consequence for tires of the smaller sizes employed upon many passenger vehicles. However, it has been found that in tires of the size employed upon light utility vehicles, such as vans, pickup trucks and the like, the rim stresses generated by radial tires can exceed the structural strength of the conventional rims, with the result of possible failure of the rim especially in the well region when the rims are of the drop center type and are constructed by welding two or more components together. The problem has been especially acute for rims of the so-called tapered bead type, adapted to receive tubeless tires, on wheels of the 16.5 inches diameter size employed for light duty utility vehicles.
A similar defect had not been experienced with rims of the same type employed with bias carcass tires of like size probably because the diagonal disposition of the carcass cords results in distributing the stresses over a larger arc of the rim circumference and, hence, the load is not concentrated to the same extent as occurs when the carcass reinforcement is essentially radial.